The anterior surface of the eye is covered by several physically contiguous but histologically distinct epithelia overlying the cornea, limbus and conjunctiva. As self-renewing tissues, these epithelia are governed by stem cells which play a crucial role in tissue homeostasis, regeneration and tumorigenesis. Our earlier work has helped to establish that corneal epithelial stem cells are preferentially located in the limbal zone. This finding has improved our understanding of corneal epithelial diseases and their treatment. Much less is known, however, about the location of conjunctival epithelial stem cells. Our recent data suggests that conjunctival epithelial stem cells are enriched in the fornical zone, and that conjunctival goblet cells are able to divide and thus may play a role in maintaining and repairing the conjunctival epithelium. The long-term goal of this project is to understand the biological properties of corneal and conjunctival epithelial stem cells. Towards this end we will: (i) localize the conjunctival epithelial stem cells, by in vitro and in vivo experiments comparing the proliferative properties of bulbar, fornical and palpebral epithelial cells; (ii) determine the role of the goblet cell in conjunctival homeostasis, by light and transmission electron microscopy, cell culture, autoradiography and a athymic mouse/epithelial cyst system; and (iii) identify proteins elaborated by fibroblasts underlying~the corneal, limbal and conjunctival epithelia using the random primer-PCR technique. Data obtained from these studies, should help us understand the role of stem cells in corneal and conjunctival epithelia in growth control and differentiation. These studies should ultimately lead to a better understanding and therapy of ocular surface disorders including persistent corneal epithelial defect and various dry-eye conditions.